Irradiation conversion of paraffins



' 10 -10 rep is the preferred practice.

United States Patent 3,177,132. IRRADIATIGN CONVERSION OF P 1 FiNS Alexander T. Wilson, Wellington, New Zealand, and David A. McCaulay, Homewood, ilL, assignors to Standard Oil Company, Chicago, 111., a corporation of Indiana No Drawing. Filed Dec. 30, 1958, Ser. No. 783,689 18 Claims. (Cl. 204-154) olefins, are commercial processes of extreme importancein meeting present day motor fuel octane requirements. Alkylate and polymer gasolines are both highly valued, and the national production of each runs to many thousands of barrels per day. These processes, depending on the particular feedstocks employed, concurrently yield large quantities of substantially olefin-free light hydrocarbons. With the exception of isobutane, these are nonreactive and ordinarily cannot be converted to liquid I products in the motor fuel boiling range without prior use of expensive catalytic isomerization or dehydrogenation. r

We have now discovered" a process whereby the light hydrocarbons propane, normal butane, isobutane and their admixtures, which may be obtained as co-products from alkylation or polymerization processes, can be converted directly to liquidproducts suitable as motor fuel blending components. Specifically, we have discovered that when these light, normally gaseous hydrocarbonsare liquified and, in the substantial absence of olefins, subjected to sufficient beta or gamma radiation, valuable liquid products of the motor fuel boiling range are produced. In contrast to the radiation-induced paraffinolefin 'alkylation or olefin-olefin polymerization where some heavy polymer is obtained, the liquid products of the instant process boil substantially entirely in the motor fuel range (about 400 F. maximum final boiling point) and can be utilized directly without need for product rerunning. a Thus, according to the invention, a feedstock comprising a substantially olefin-free parafiin having from three to four carbon atoms, inclusive, per molecule is charged to a reaction zone Where it is exposed in the liquid phase to beta and/or gamma radiation. A suitable dosage is between about and 10 rep (roentgen equivalent physical) with the dosage controlled in conventional manner by varying the radiation fiux and reactant residence time, or both. Irradiation to a dosage of about Either after the radiation processing or, if desired, during irradiation, liquid products are separated in any suitable manner from the reaction mixture. Unconverted reactants may optionally be separated and recycled to the reaction zone for reprocessing, while the liquid products are sent to storage.

Feedstocks for the present process are propane, normal butane, isobutane, and their admixtures with each other. These light parafiin hydrocarbons may be obtained in substantially olefin-free form from a wide variety of processes. Thermal and catalytic cracking operations yield a mixture of propane, propylene, butanes, and butylenes. When polymerizing either the propane-propylene or butane-butylene fraction, only the olefins react, and the resultant parafiinic, substantially olefin-free, co-products may be employed herein. Similarly, alkylation consumes only olefins and isoparafiins, while the unconverted normal parafiins are available as feedstocks in our process. Another source of light paraffins is the material consisting predominately of propane and butanes which is recovered as an overhead distillate in the stabilization of casinghead gasoline, the liquid fraction of natural gas. A similar light paraffin mixture is obtained when stabilizing virgin petroleum gasoline. It is of special note that the normal paraifins propane and normal butane, as well as isoparaflins, are suitable feedstocks.

Radiation which efiects the desired hydrocarbon conversion is either beta particles or gamma electromagnetic radiation, or both types. As employed herein, throughout the specification and claims, the term beta relates to electrons, Whether derived from nuclear disintegration reactions (beta 'decay), orbital electron removal (Compton scattering, photoelectric effect), electron generating apparatus (cathode ray tubes, Van de Graaif generators, linear accelerators), or other sources. Likewise, the term gramma is taken in its broad sense to denote electromagnetic radiation having a Wave length of between about 10" and about 10 cm., from whatever source derived. Gamma rays may be obtained from nuclear disintegration (fission, spallation, beta-gamma energy predominating. Waste fission products, which 7 are the primary fission fragments and their decay products obtained from nuclear fission processes, are both useful and low-cost sources. Material made radioactive by exposure to neutrons in a nuclear reactor, such as cobalt-60, may be utilized as a high intensity gamma (and low energy beta) source. In large installations, the reactants may be irradiated by the flux in or from a nuclear reactor; if desired, the reactants may constitute all or a part of the moderator for such nuclear reactor. It is preferred that the radiation source be of sufiicient strength to supply at least about 10 rep per hour.

Ordinarily, the present radiation-induced reaction is conducted at ambient temperatures although reduced temperatures or somewhat elevated temperatures, in the range of to +150 C. (or more ranging up to the incipience of thermal cracking) may be used. Since a liquid phase appears to be necessary in order toacbieve satisfactory radiation utilization, the system pressure should be sufiicient to assure the maintenance of a liquid phase 7 in the reaction zone.

In applying the process, a recycle type flow system is preferred in which the paraflin feed is charged to the reaction zone and the resulting reaction mixture is conducted to a separate fractionation zone. The products are withdrawn as a bottoms fraction and selected fractions are recycled, while light uncondensible gases may be purged or collected for any desirable use. Hydrogen is evolved as an uncondensible gas in the proportion of about 0.5-1 mole per mole of liquid hydrocarbon product. Some methane is also formed. Most of the normally liquid product consists of branched hydrocarbons in the C C range, with little or no product having a higher boiling point. As a result, the liquid may be utilized as a motor fuel or motor fuel component without re-running.

Illustrative embodiments of the invention are depicted in the specific examples presented below. These examples are intended to show particular embodiments and are not to be" considered definitive with respect to conditions, procedure, or scope.

I5 Example I In this example, a feedstock consisting of normal butane was converted to liquid products by the action of gamma rays.

One hundred-twelve parts by weight of n-butane was sealed in a pressure-containing bomb under suiiicient pressure to maintain a liquid phase at room temperature. The bomb was exposed to a radiation dose of 10 rep of gamma rays from spent nuclear reactor fuel elements in a canal type facility in which the fuel elements were stacked vertically. The fuel elements had been obtained from a water moderated thermal neutron reactor, and were capable of emitting a maximum flux of 10 roentgens per hour. After radiation to the above mentioned 10 rep dosage level, the bomb was lifted from the canal, scrubbed to remove contaminants, and shipped to a processing laboratory. There the bomb contents were fractionally distilled to separate non-condensible gases (89% H 6 methane), 97 parts of unconverted butane, and two parts of liquid product.

The above liquid product was redistilled to determine the following compositional analysis:

Liquid product composition: Vol. percent C5 N11 C 50 C Nil 50 C and heavier Nil Chromatographic analysis indicated that the product con- 9 sisted chiefly of branched, high-octane number, components.

Example I] Run 1 Run 2 Run 3 Feedstock:

Isobutane, parts by weight 93 84 Isobutylene 121 18 Liquid product yield, wt. percent. 2. 1 4. 5 6. 9 Liquid product composition:

C vol. percent nil nil 8a 30 ml nil 7 C8 70 35 60 C nil nil nil 81onil nil nil ll 111 Cm m1 2s 30 013-17 nil nil nil C1 and higher nil 4O In Run 1, according to the invention, the liquid products were essentially all in the C -C boiling range and were suitable for blending into motor gasolines without any rerunning. By contrast, in the radiaton-induced polymerization of Run 2, and in the radiation-induced alkylation of Run 3, fractionation of the products is required to obtain a motor fuel component.

Example III In this example, a mixture of isobutane (55 parts) and propane (52 parts) was irradiated under the conditions of Example I. Liquid product was recovered in a four weight percent yield with a dosage of 10 rep. the following composition:

It had Liquid product composition: Vol. percent C Nil C 50 C 25 C 25 C and higher Nil Example IV In this example, a mixture of normal butane (54 parts) and propane (50 parts) was irradiated under the conditions of Example I. With a dosage of 10 rep, two percent of the following liquid composition was obtained:

Liquid product composition: Vol. percent From the foregoing presentation and examples, it is manifest that valuable liquid products may be obtained from the parafiins propane, normal butane, and isobutane by subjecting a feedstock consisting essentially of one or more of these paraffin's in the liquid phase to the action of beta or gamma rays.

We claim:

1. A non-catalytic process forthe conversion of light paraffins to liquid products boiling above butane which comprises: charging to a reaction zone a feed stock consisting essentially of a light paraffin having from three to four carbon atoms, inclusive, per molecule; subjecting said paraffin as a liquid in said reaction zone to a total dosage of from about 10 to about 10 rep of gamma and beta rays as the sole effective conversion agents; and separating the resultant liquid products from the resulting reaction mixture.

2. Process of claim 1 wherein at least a portion of the unconverted material is separated from the reaction mixture and recycled to the reaction zone.

3. Process of claim 1 wherein said light paraffin comprises propane.

4. Process of claim 1 wherein said light parafiin comprises normal butane.

5. Process of claim 1 wherein said light parafiin comprises isobutane.

6. Process of claim 1 wherein said radiation dosage is from about 10 to about 10 rep.

7. A non-catalytic process for the conversion of light parafiins to liquid products boiling above butane which comprises: charging to a reaction zone a feedstock consisting essentially of a light parafiin having from three to four carbon atoms, inclusive, per molecule; subjecting said paralfin as a liquid in said reaction zone to a dosage of from about 10 to about 10 rep of beta rays as the sole effective conversion agent; and separating the resultant liquid products from the resulting reaction mixture.

8. Process of claim 7 wherein at least a portion of the uncoverted material is separated from the reaction mixture and recycled to the reaction zone.

9. Process of claim 7 wherein said light parafiin comprises propane.

10. Process of claim 7 wherein said light paraffin comprises normal butane.

ll. Process of claim 7 wherein said light parafiin comprises isobutane.

12. Process of claim 7 wherein said radiation dosage is from about 10 to about 10 rep.

13. A non-catalytic process for the conversion of light paraffins to liquid products boiling above butane which comprises: charging to a reaction zone a feedstock consisting essentially of a light parafiin having from three to four carbon atoms, inclusive, per molecule; subjecting said paraffin as a liquid in said reaction zone to a dosage of from about 10 to about 10 rep of gamma rays as 2,743,223 4/56 McClinton et al 204-154 the sole effective conversion agent; and separating the 2,372,396 2/59 Wil t 1, 104 162 resultant liquid products from the resulting'reaction mix- 2,955,942 10 0 Kitt 'edge 20 5 ture.

14. Process of claim 13 wherein at least a portion of 5 FOREIGN PATENTS the unconverted material is separated from the reaction 1 148 720 6/57 France mixture and recycled to the reaction zone.

15. Process of claim 13 wherein said light paraffin OTHER REFERENCES comprises propane.

Process f claim 13 wherein Said light pamfltin 1O Lind et al.: Jour. Amer. Chem. Soc., vol. 48 (Septemcomprises normal butane. Pages 17. Process of claim 13 wherein said light parafiin Charlesby: Atomic Radiation and Polymers, 1960, comprises isobutane. page 42, V

18. Process of claim 13 wherein said radiation dosage Tolbert et Radiation Research, VOL 3, Na 1 is from about 10 to about 10 rep. 5' pages 52 57I September 1955 References Cited by the Examiner UNITED STATES PATENTS 1,961,493 6/34 Hillis 204-1581 JOSEPH REBOLD, JOHN R. SPECK, Examiners.

JOHN H. MACK, Primary Examiner. 

1. A NON-CATALYTIC PROCESS FOR THE CONVERSION OF LIGHT PARAFFINS TO LIQUID PRODUCTS BOILING ABOVE BUTANE WHICH COMPRISES: CHARGING TO A REACTION ZONE A FEED STOCK CONSISTING ESSENTIALLY OF A LIGHT PARAFFIN HAVING FROM THREE TO FOUR CARBON ATOMS, INCLUSIVE, PER MOLECULE; SUBJECTING SAID PARAFFIN AS A LIQUID IN SAID REACTION ZONE TO A TOTAL DOSAGE OF FROM ABOUT 10**6 TO ABOUT 10**10 REP OF GAMMA AND BETA RAYS AS THE SOLE EFFECTIVE CONVERSION AGENTS; AND SEPARATING THE RESULTANT LIQUID PRODUCTS FROM THE RESULTING REACTION MIXTURE. 